Along with the popularity of smart mobile terminals, such as mobile phones and tablets, and rapid development of the mobile Internet, the number of smart mobile terminals used by users is increasing. A photographing function has become one of standard configurations of a smart mobile terminal. People use mobile terminals instead of professional cameras to take photos in most occasions of daily life because existing mobile terminals have an increasingly powerful photographing capability and are easy to carry. People's requirements for recording beautiful moments always exist, and are even becoming stronger. However, in the prior art, it takes some time for a camera application in a mobile terminal to start up. It frequently happens that when a person takes out a mobile terminal, scenery of which the person wants to capture a photo no longer exists after the mobile terminal powers on hardware used for photographing, enables a sensor and an image signal processor, and starts a camera application to take a photo. Therefore, the beautiful moments that a person wants to record are easy to be missed.